What Hogwarts-related book did J.K. Rowling publish under the fictional author Kennilworthy Whisp?

J.K. Rowling published Quidditch Through the Ages under the fictional author name Kennilworthy Whisp.

The book is presented as a Hogwarts library volume about the history and rules of Quidditch, the wizarding sport played on broomsticks. In the real world, Bloomsbury published it in 2001 as a charity companion book, with proceeds supporting Comic Relief.

Its mock-scholarly format gives the fictional world extra detail, including accounts of broom games, Quidditch equipment, fouls, and international teams. The book’s credited author is not Rowling inside the story; Kennilworthy Whisp is an invented wizarding writer.

This title is often mixed up with Fantastic Beasts and Where to Find Them, another charity companion book from the same period. Fantastic Beasts is credited in-world to Newt Scamander, while Quidditch Through the Ages is credited to Whisp.